Molecular Approaches Toward Manipulating the Expression of the Glucose-Regulated Proteins in Mammalian Cells

Abstract

Since the discovery of the glucose-regulated proteins (GRPs) in 1977 as a set of mammalian proteins specifically induced in cultured cells deprived of glucose in their culture medium (1), much progress has been made toward identifying the physiological functions played by these stress-inducible proteins (2, 3). The GRPs are organelle proteins localized in the endoplasmic reticulum (ER), and they include GRP94, GRP78, ERp72, and GRP58, with respective molecular sizes of 94, 78, 72, and 61 kd (4, 5). GRP94 is also referred to as ERp99 (6) or endoplasmin (7). Interestingly, these proteins all bear some functions related to protein folding and processing in the ER, and their genes appear to be coordinately regulated at the transcriptional level by a variety of stress conditions affecting protein trafficking in the ER (5, 8–11).